Finally, interrupts are useful because there is one point where an interrupting character has an advantage, (in my opinion, its not expressed directly in the rules but it makes logical sense.) which is when an opponent is charging an attack. If your character is able to recognise this, or just spots a lapse in concentration on the battle (which is more than fair) and strikes, the opponent would most likely have to cancel their charge, or face a reduced reaction time to said interruption attack.

Though that's up to interpretation.